Thanks a lot for your advice or solutions :

my goal is also to releave my speaker woofers (as well as my main tube amplifier) from the burden of the sub 60Hz-or-so-bass, and to be more agile above that range.

By the way, here is a very good audio Podcast, I think, on the subject of bass integration :
https://darko.audio/2022/01/podcast-30- … nd-beyond/

I’d suggest to use an external analog or digital X-Over.

(Mis-)using an equalizer as crossover has never been a good idea, too many important features are missing.

Additional to the:
• Filter Frequencies,
• Filter Q
offered by ADI-2, you need the choice of:
• Filter type (Bessel, Butterworth, Linkwitz-Riley),
• Filter Slope (6, 12, 18 dB/Octave),
• Phase adjustment.
• Satellite delay.

Pro does not

Right. For crossover, you'll need to use hardware solutions such as MiniDSP, or software solutions such as CamillaDSP. ADI-2 is not designed for this use case.

Thank you Ning, CAMILLIA sounds as a very good solution as i have a RaspberryPi 3-based streamer.

especialy if time alignement and room correction is involved too.

appart from this Digione Signature streamer, my system is as follows :

OK, the solution:

The idea is, to boost the system’s bass response with the sub, then linearize the response again with ADI-2 DAC’s equalizer.

This way the main speakers and amp is relieved from parts of the bass load, but still contribute to the bass in a favorable way.

This approach largely avoids bloated bass from a slow sub, as the much faster main speakers still serve for the bass transients.
Even room coupling usually works better with still multiple bass sources.

Here we go:

How to setup ADI-2 DAC in a setup with
main speaker+subwoofer.

The following sounds a bit lengthy and complicated, but is in fact quite straigth forward and can be fun.

What we need:

• iPhone/iPad with "RTA“ by Andrew Smith, 5.49€ in the Appstore, try out is free:
https://apps.apple.com/de/app/rta/id298839433
Or the AudioTools suite (we only use RTA):
https://apps.apple.com/de/app/audiotools/id325307477

• Something to place the iDevice in free air at the listener's position, e.g. a photo tripod, a selfiestick, or any stick+tape, or any mount.
Don't lay the iDevice on something big, this would disturb the soundfield around the mic.

• Pink noise from any source.
The AudioTools' RTA has a generator built in.
You can either connect this iDevice, or a 2nd one with the same app (that's what I usually do), or use PinkNoise from a CD or from Youtube:
https://m.youtube.com/watch?v=ZXtimhT-ff4

• In AudioTools RTA's Setup "Mic Compensation Filter", and "Measurement Mode" should be Enabled.
Set "Output Mode" to "Mono", not "Balanced"!

• Switch OFF the subwoofer.
• Set RTA to 1/3 Okt., 30s Decay.
• Look at the room noise.
• Play the Pink Noise.
• Dial in a Pink Noise level 15-20dB above room noise.
The average from 100Hz to 1kHz should meet a scale line, as reference line.
• Switch OFF the main speakers, ON the sub.
• On the sub's controls, set the level at 10dB above the the RTA's reference line, with sub's x-over frequency try to find a range between 60-110Hz that looks the most linear. Make a pencil mark.
• On ADI-2 DAC, use the lowest EQ band: Shelving, Level -8dB, f=like sub, Q=0,7, as a startpoint..

• Now, switch the main speakers ON too, linearize the response by playing with:
- the sub's phase switch,
- the EQ settings, but only the low band.
- the sub's frequency control around the pencil mark,
- and a bit with the sub's room placement if possible.

These are all interactive.

Goal is a slightly, 3dB, elevated bass and a relatively linear bass response.
With a good setting you can counteract room modes too.
Don't care about higher frequencies at this point.

Take notes when you found a good setting before trying another.
Listen to music inbetween if you found a good setting.

> - Camilla DSP
  but if it works in the digital domain is it able to filter differently my speakers from my sub ? It's a bit abstract to me at this point.
  But i suspect this solution can do a lot (for room correction, phase...)

Of course, it has endless possibilities and plenty of filters for you to choose from.
You can even use FIR filters to correct phase, which is not possible with EQ.
With measurement mics you can do crossover and frequency-response/phase correction to the optimal accuracy.
(If you have time, you can even correct the phase of each woofers and tweeters! Analog hardware simply cannot achieve that.)
The official doc has samples for crossover.
Unlike FPGA/DSP solution ADI-2 uses, CamillaDSP runs on your OS and needs CPU power for processing (thus has some latency) though.

With Linux 5.18 (will be released in a few months), one can use a Linux machine (such as a Raspberry Pi) as a simple digital interface --- you connect the RPi to your PC/Mobile device, and it will be recognized as a standard audio interface like the ADI-2. You send music signals in, and it can DSP your input audio and send it out to a standard DAC (such as ADI-2). I currently have a RPi that do exactly what ADI-2 can do (crossfeed, EQ, loudness, etc) and it can be used just like a regular audio interface.

thanks all, thats realy helpful.

(-: though i will have to find some time off to experiment all this, like :
microphone mesurements / your setup KaiS / REW / filtering tests, etc...)

To finish with :

do you see major differences between those two approches ?
- Via mesurement and DAC EQ
- or via CamillaDSP

I mean, major differences that possibly make things much easier,
OR that make a palpable sonic improvement ?

"Phase Correction", that Ning mentioned, I suppose is one fairly big difference.

The most obvious difference:
You won’t need to buy anything with my approach, neither need to reconfigure your system.

Frederic47 already has an ADI-2 DAC, a measurement mic and REW.

For averaging various measurement positions slowly move the mic over the desired range.
This simulate the professional solution using a rotating boom, or multiple mics and an automatic switcher.
I have one and never use it, too time consuming to setup.

Usually I start static, at my listening position.
Finally rotate the mic by hand over an extended area.

Labor: last time I did it for fun it took 10 min.
Specially with the iPhone it’s so simple, setup time: zero.
But as setup options are limited. the outcome is a bit a matter of luck for a given system.